stupidgcm: unexport stupidGCM struct

No need to have it exported.

internal/stupidgcm/common_test.go

@@ -215,7 +215,7 @@ func testOpenAllZero(t *testing.T, c cipher.AEAD) {
 
 func testWipe(t *testing.T, c cipher.AEAD) {
 	switch c2 := c.(type) {
-	case *StupidGCM:
+	case *stupidGCM:
 		c2.Wipe()
 		if !c2.Wiped() {
 			t.Error("c2.wiped is not set")

internal/stupidgcm/gcm.go

@@ -21,20 +21,19 @@ const (
 	tagLen = 16
 )
 
-// StupidGCM implements the cipher.AEAD interface
-type StupidGCM struct {
+type stupidGCM struct {
 	stupidAEADCommon
 }
 
 // Verify that we satisfy the interface
-var _ cipher.AEAD = &StupidGCM{}
+var _ cipher.AEAD = &stupidGCM{}
 
 // New returns a new cipher.AEAD implementation..
 func New(keyIn []byte, forceDecode bool) cipher.AEAD {
 	if len(keyIn) != keyLen {
 		log.Panicf("Only %d-byte keys are supported", keyLen)
 	}
-	return &StupidGCM{
+	return &stupidGCM{
 		stupidAEADCommon{
 			// Create a private copy of the key
 			key:              append([]byte{}, keyIn...),